I find it's often faster for me to finish the final 20% myself than to talk the agent into doing it for me; because too often the agent will start to eat its own tail, and spend far too long completing something that I find obvious.

Yes, and English/natural language is not necessarily more concise than programming languages, if you need to describe something precisely.

For example, I was recently trying to get an agent to debug something which was difficult to debug because it ran in an exotic context, where debuggers and logging and printf couldn't easily reach. The agent kept coming up with more and more elaborate and smart-sounding theories and debugging strategies, but nothing worked. I stupidly kept going with this for like 20 minutes, until finally I just went into an IDE, did a simple "comment bisection" where I commented stuff out until I found the line that was breaking, and found and fixed the problem in five minutes. So I solved it by typing code. The code I typed: "//" (in about six places). I could probably have gotten the agent to do the same thing but would have actually literally had to type more to explain to the agent what I wanted. In fact it took me longer to write this comment describing what I did here than it did to just do it.